The invention herein is directed to a process for preparing prostaglandins of the PGE series. The invention herein is also directed to novel prostaglandin compounds and more specifically, prostaglandin intermediates or precursors.
Prostaglandin derivatives can be prepared utilizing vinylstannane compounds which are reacted with an alkyl lithium compound and subsequently with an organo copper compound and then with a cyclopentenone to provide the prostaglandin derivative. In such reaction the hydroxyl group on the omega side chain is protected. The vinylstannanes are employed to add the omega side chain of the prostaglandin derivatives, therefore it is important that the olefin geometry of the vinylstannenes be a trans configuration as the olefin geometry of the PGE prostaglandin derivatives is a trans configuration between the 13 and 14 carbon atoms.
U.S. Pat. Nos. 4,499,296; 4,322,543; 4,578,505; and 4,271,314 describe organo tin intermediates which are useful in the preparation of prostaglandin derivatives. U.S. Pat. Nos 4,777,275 and 4,785,124 describe higher order cuprate complexes which can be formed from vinylstannane compounds and which are then subsequently used in the production of prostaglandin derivatives.
A common method for synthesizing vinylstannanes involves the hydrostannylation of alkynes. This approach when used to produce prostaglandins has heretofore required the isolation, purification and protection of the intermediates. The term protection is used to signify the addition of a group to protect the hydroxyl groups which eventually result on the pentane ring and the omega side chain of the prostaglandin to be formed.
It would be desirable to provide a process for producing prostaglandins with sufficient specificity for the trans configuration in a one pot reaction wherein the steps of isolating, purifying and protecting the intermediates can be avoided.